Planar terahertz filter with narrow passband and low insertion loss.

How to reduce the bandwidth and insertion loss (IL) of a planar filter at high frequency is challenging work. We investigate the design, simulation, fabrication, and measurement of a terahertz (THz) planar filter with easy integration, low IL, and narrow passband. The direct feeding microstrip filter (DFMF) has a center frequency (f0) of 140 GHz, IL of 2 dB, and 3 dB fractional bandwidth (FBW3dB) of 6%, while traditional coupled feeding microstrip filter with the same configurations has FBW3dB of 20%. The proposed DFMF filter employs direct feeding mode to narrow bandwidth and miniaturized size. The DFMF does not need small coupling gaps in the feeding structures, showing good dimensional insensitivity. Benzocyclobutene is introduced as an interlayer dielectric to reduce IL owing to its controllable ultrathin thickness and low-loss tangent. The introduced planar microelectromechanical system technology is suitable for large-scale fabrication at a low cost. The test results based on through-reflect-line de-embedding technology agree well with the simulation results. The DFMF lays a foundation for realizing the planarization and integration of THz systems.

Local administration of siRNA through Microneedle: Optimization, Bio-distribution, Tumor Suppression and Toxicity.

Although RNA interference may become a novel therapeutic approach for cancer treatment, target-site accumulation of siRNA to achieve therapeutic dosage will be a major problem. Microneedle represents a better way to deliver siRNAs and we have evaluated for the first time the capability of a silicon microneedle array for delivery of Gapdh siRNA to the skin in vivo and the results showed that the microneedle arrays could effectively deliver siRNA to relevant regions of the skin noninvasively. For the further study in this field, we evaluated the efficacy of the injectable microneedle device for local delivery of siRNA to the mouse xenograft. The results presented here indicate that local administration of siRNA through injectable microneedle could effectively deliver siRNA into the tumor region, and inhibit tumor progression without major adverse effects.